The boys found the two professors busy adjusting some of the delicate scientific instruments with which they expected to make observations on the trip, and after they reached the moon.
"What is your opinion, Professor Roumann, of the temperature at the moon's surface?" asked Mr. Henderson.
"I am in two minds about it," was the reply. "A few years ago, I see by an astronomy, Lord Rosse inferred from his observations that the temperature rose at its maximum (or about three days after full moon) far above that of boiling water."
"Boiling water!" ejaculated Mark. "Wow! That won't be very nice. I don't want to be boiled like a lobster!"
"Wait a moment," cautioned Mr. Roumann, with a smile. "Later, Lord Rosse's own investigations, and those of Langley, threw some doubts on this. There is said to be no air blanket about the moon, as there is about the earth, so that the moon loses heat as fast as it receives it; and it now seems more probable that the temperature never rises above the freezing point of water, just as is the case on our highest mountains."
"That's better," came from Jack. "We can stand a low temperature more easily than we can to be boiled; eh, Jack?"
"Sure. But I don't want to be frozen or boiled either, if I can help it. Guess I'll wear my fur suit that we brought back from the North Pole with us."
"I agree with you, Professor Roumann, about the temperature," announced Mr. Henderson, "so we must make up our minds to shiver, rather than melt. But we are prepared for that."
"What about there being no air on the moon?" asked Jack.
"Oh, we can manufacture our own oxygen," said Mark. "We can walk around with an air tank on our shoulders, as we did when we went beneath the surface of the ocean. Now, I guess——"